The present invention relates generally to pump jacks and more specifically to hydraulic pump jacks for oil wells and other applications.
Oil well pump jacks have traditionally consisted of complex mechanical devices with linkage units for transforming rotary motion from motors into the reciprocating motion needed for pumping. Conventional pump jacks generally require a relatively large amount of space in order to provide adequate clearance for the various moving parts and have necessarily been positioned aboveground. These pump jacks also require firmly anchored base supports or support pads in order to properly align the drive unit of the apparatus with the sucker rod of the oil well. The size and clearance requirements associated with traditional oil well pump jacks have proven to be a problem in agricultural areas utilizing center pivot irrigation systems and other large farm machinery. In addition, above ground pump jacks tend to be noisy and unsightly, thereby making oil wells aesthetically undesirable in populated or scenic areas. A further disadvantage of conventional pump jacks is the tendency of systems having multiple moving parts to break down at frequent intervals. If the number of moving parts in such systems are reduced, then desirable pumping characteristics having to do with pump stroke length and speed are generally sacrificed.
A need exists for an oil well pump jack which is reliable and which can also operate in a confined space. The pump jack should be capable of adaptation to different types of oil wells and should be capable of providing desirable pump stroke performance.